Structure, Conformational Equilibrium, and Proton Affinity of Calix[4]arene by Density Functional Theory

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 1999-11, Vol.103 (45), p.9080-9085
• Main Authors: Bernardino, R. J, Cabral, B. J. Costa
• Format: Article
• Language: English
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp991213h

Density functional theory results for the structure and conformational equilibrium of four calix[4]arene conformers are reported. The results are compared with experiment, force field, and semiempirical molecular orbital calculations. The energy difference between the two most stable conformers of calix[4]arene (cone and partial-cone) is 10 kcal mol-1 at the BLYP/6-31G** level with the geometries optimized at BLYP/6-31G*. For the most stable conformer, results for the protonated structure are also reported. Electrostatic potential surfaces for the cone calix[4]arene and the corresponding tetra-O−H-depleted structure have been calculated. It is suggested that their representation may be of relevance to understand the known ability of calix[n]arene systems to form complexes with charged species in host−guest chemistry.